THE OSTEOLOGY OF ELOTHERIUM. 311 
quite widely expanded in the transyerse direction; and in shape recalls that seen in the 
camels and llamas. The head is almost hemispherical in form and has a small, deep pit 
for the round ligament; it is set upon a very distinct neck, which is connected by a long, 
narrow bridge of bone with the great trochanter. The latter is very large and massive, 
especially in the antero-posterior direction, but does not rise above the level of the head, 
and hence is not very conspicuous, when the femur is seen from the front. The digital 
fossa is deep and widely open, which is due to the great thickness of the trochanter, but 
is not much extended in the vertical direction. The second trochanter is also large and 
very rugose, but not very prominent; it projects almost entirely backward, so that the 
trochanter is hardly visible, when the bone is viewed from the anterior side. There is no 
plainly marked intertrochanteric ridge, connecting the great and second trochanters, but 
from the latter a ridge runs proximally and almost reaches to the head. 
The shaft of the femur, which in its proximal portion is much expanded transversely 
and compressed antero-posteriorly, rapidly narrows downward, and below the second 
trochanter becomes quite slender and subeylindrical in shape. Toward the distal end 
the shaft widens considerably, though increasing little in thickness. Above the external 
condyle is a long, narrow pit, with rugose margins, which serves for the origin of the 
plantaris muscle. The rotular groove is very broad, but quite shallow; its inner border 
is much thicker and more prominent than the outer, and ascends higher proximally, 
where it terminates in a short, overhanging hook, while the external border dies away 
more gradually. The condyles are relatively small; they present directly backward, 
though not projecting very strongly behind the plane of the shaft, and are of almost 
equal size, the external one but slightly exceeding the internal in height and breadth. 
The intercondylar fossa is broad and deep and has nearly straight borders. 
The proportionately small antero-posterior diameter of the distal part of the femur 
in Elotherium is in decided contrast to the thickness of this region in Ancodus. The 
femur of Anthracotherium is much like that of Hlotherium, but it is even more slender 
in proportion to its length, and the condyles are smaller. Sws has a femur of quite a 
different type; the proximal end is not so wide, the head is more sessile and has a much 
larger pit for the round ligament; the bridge connecting the head with the great 
trochanter is shorter and much thicker, and the trochanter itself is more prominent ; the 
shaft is relatively less elongate, the rotular grooye has borders of nearly equal height, 
and the condyles are more prominent. The femur of Hippopotamus, though extremely 
massive, has yet a certain resemblance to that of Hlotheriwm, as may be seen in the 
transverse expansion of the proximal end and in the obliquity and asymmetry of the 
rotular groove. 
The patella is large, massive and of rather peculiar shape. It is high, quite broad 
An Ps S—SVOll, IDK, BR 
